Syphilis is a sexually transmitted infection caused by the bacteriumTreponema pallidum subspecies pallidum.[1] The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and tertiary). The primary stage classically presents with a single chancre (a firm, painless, non-itchy skin ulceration) but there may be multiple sores. In secondary syphilis a diffuse rash occurs, which frequently involves the palms of the hands and soles of the feet. There may also be sores in the mouth or vagina. In latent syphilis, which can last for years, there are little to no symptoms.[2] In tertiary syphilis there are gummas (soft non-cancerous growths), neurological, or heart symptoms.[3] Syphilis has been known as "the great imitator" as it may cause symptoms similar to many other diseases.[2][3]

Syphilis is most commonly spread through sexual activity.[2] It may also be transmitted from mother to baby during pregnancy or at birth, resulting in congenital syphilis.[2][4] Other human diseases caused by related Treponema pallidum subspecies include yaws (subspecies pertenue), pinta (subspecies carateum), and bejel (subspecies endemicum).[3] Diagnosis is usually made by using blood tests; the bacteria can also be detected using dark field microscopy. The Center for Disease Control recommends all pregnant women be tested.[2]

In 2012 about 0.5% of adults were infected with syphilis with 6 million new cases.[5] During 2010 it caused about 113,000 deaths, down from 202,000 in 1990.[6] After decreasing dramatically with the availability of penicillin in the 1940s, rates of infection have increased since the turn of the millennium in many countries, often in combination with human immunodeficiency virus (HIV).[3][7] This is believed to be partly due to increased promiscuity, prostitution, decreasing use of condoms, and unsafe sexual practices among men who have sex with men.[8][9][10] In 2015, Cuba became the first country in the world to eliminate mother-to-child transmission of syphilis.[11]

Signs and symptoms

Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary,[3] and may also occur congenitally.[12] It was referred to as "the great imitator" by Sir William Osler due to its varied presentations.[3][13]

Primary

Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person.[14] Approximately 3 to 90 days after the initial exposure (average 21 days) a skin lesion, called a chancre, appears at the point of contact. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders 0.3–3.0 cm in size.[3] The lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer.[15] Occasionally, multiple lesions may be present (~40%),[3] with multiple lesions more common when coinfected with HIV. Lesions may be painful or tender (30%), and they may occur in places other than the genitals (2–7%). The most common location in women is the cervix (44%), the penis in heterosexual men (99%), and anally and rectally relatively commonly in men who have sex with men (34%).[15]Lymph node enlargement frequently (80%) occurs around the area of infection,[3] occurring seven to 10 days after chancre formation.[15] The lesion may persist for three to six weeks without treatment.[3]

Secondary

Typical presentation of secondary syphilis with a rash on the palms of the hands

Reddish papules and nodules over much of the body due to secondary syphilis

Latent

Latent syphilis is defined as having serologic proof of infection without symptoms of disease.[14] It is further described as either early (less than 1 year after secondary syphilis) or late (more than 1 year after secondary syphilis) in the United States.[18] The United Kingdom uses a cut-off of two years for early and late latent syphilis.[15] Early latent syphilis may have a relapse of symptoms. Late latent syphilis is asymptomatic, and not as contagious as early latent syphilis.[18]

Tertiary

Tertiary syphilis may occur approximately 3 to 15 years after the initial infection, and may be divided into three different forms: gummatous syphilis (15%), late neurosyphilis (6.5%), and cardiovascular syphilis (10%).[3][18] Without treatment, a third of infected people develop tertiary disease.[18] People with tertiary syphilis are not infectious.[3]

Gummatous syphilis or late benign syphilis usually occurs 1 to 46 years after the initial infection, with an average of 15 years. This stage is characterized by the formation of chronic gummas, which are soft, tumor-like balls of inflammation which may vary considerably in size. They typically affect the skin, bone, and liver, but can occur anywhere.[3]

Neurosyphilis refers to an infection involving the central nervous system. It may occur early, being either asymptomatic or in the form of syphilitic meningitis, or late as meningovascular syphilis, general paresis, or tabes dorsalis, which is associated with poor balance and lightning pains in the lower extremities. Late neurosyphilis typically occurs 4 to 25 years after the initial infection. Meningovascular syphilis typically presents with apathy and seizure, and general paresis with dementia and tabes dorsalis.[3] Also, there may be Argyll Robertson pupils, which are bilateral small pupils that constrict when the person focuses on near objects but do not constrict when exposed to bright light.

Cardiovascular syphilis usually occurs 10–30 years after the initial infection. The most common complication is syphilitic aortitis, which may result in aneurysm formation.[3]

Cause

Bacteriology

Treponema pallidum subspecies pallidum is a spiral-shaped, Gram-negative, highly mobile bacterium.[7][15] Three other human diseases are caused by related Treponema pallidum subspecies, including yaws (subspecies pertenue), pinta (subspecies carateum) and bejel (subspecies endemicum).[3] Unlike subtype pallidum, they do not cause neurological disease.[4] Humans are the only known natural reservoir for subspecies pallidum.[12] It is unable to survive without a host for more than a few days. This is due to its small genome (1.14 MDa) failing to encode the metabolic pathways necessary to make most of its macronutrients. It has a slow doubling time of greater than 30 hours.[15]

Transmission

Syphilis is transmitted primarily by sexual contact or during pregnancy from a mother to her fetus; the spirochete is able to pass through intact mucous membranes or compromised skin.[3][12] It is thus transmissible by kissing near a lesion, as well as oral, vaginal, and anal sex.[3] Approximately 30% to 60% of those exposed to primary or secondary syphilis will get the disease.[18] Its infectivity is exemplified by the fact that an individual inoculated with only 57 organisms has a 50% chance of being infected.[15] Most (60%) of new cases in the United States occur in men who have sex with men. Syphilis can be transmitted by blood products, but the risk is low due to blood testing in many countries. The risk of transmission from sharing needles appears limited.[3]

It is not generally possible to contract syphilis through toilet seats, daily activities, hot tubs, or sharing eating utensils or clothing.[19] This is mainly because the bacteria die very quickly outside of the body, making transmission by objects extremely difficult.[20]

Diagnosis

This poster acknowledges the social stigma of syphilis, while urging those who possibly have the disease to be tested (circa 1936).

Syphilis is difficult to diagnose clinically early in its presentation.[15] Confirmation is either via blood tests or direct visual inspection using microscopy. Blood tests are more commonly used, as they are easier to perform.[3] Diagnostic tests are unable to distinguish between the stages of the disease.[21]

Direct testing

Dark ground microscopy of serous fluid from a chancre may be used to make an immediate diagnosis. Hospitals do not always have equipment or experienced staff members, and testing must be done within 10 minutes of acquiring the sample. Sensitivity has been reported to be nearly 80%; therefore the test can only be used to confirm a diagnosis, but not to rule one out. Two other tests can be carried out on a sample from the chancre: direct fluorescent antibody testing and nucleic acid amplification tests. Direct fluorescent testing uses antibodies tagged with fluorescein, which attach to specific syphilis proteins, while nucleic acid amplification uses techniques, such as the polymerase chain reaction, to detect the presence of specific syphilis genes. These tests are not as time-sensitive, as they do not require living bacteria to make the diagnosis.[15]

Prevention

Vaccine

As of 2010[update], there is no vaccine effective for prevention.[12] Several vaccines based on treponemal proteins reduce lesion development in an animal model, and research is ongoing.[22]

Sex

Condom use reduces the likelihood of transmission during sex, but does not completely eliminate the risk.[23] The Centers for Disease Control and Prevention states, "Correct and consistent use of latex condoms can reduce the risk of syphilis only when the infected area or site of potential exposure is protected. However, a syphilis sore outside of the area covered by a latex condom can still allow transmission, so caution should be exercised even when using a condom."[24]

Abstinence from intimate physical contact with an infected person is effective at reducing the transmission of syphilis. The CDC states, "The surest way to avoid transmission of sexually transmitted diseases, including syphilis, is to abstain from sexual contact or to be in a long-term mutually monogamous relationship with a partner who has been tested and is known to be uninfected."[24]

Congenital disease

Congenital syphilis in the newborn can be prevented by screening mothers during early pregnancy and treating those who are infected.[25] The United States Preventive Services Task Force (USPSTF) strongly recommends universal screening of all pregnant women,[26] while the World Health Organization recommends all women be tested at their first antenatal visit and again in the third trimester. If they are positive, they recommend their partners also be treated.[27] Congenital syphilis is still common in the developing world, as many women do not receive antenatal care at all, and the antenatal care others receive does not include screening, and it still occasionally occurs in the developed world, as those most likely to acquire syphilis (through drug use, etc.) are least likely to receive care during pregnancy.[25] Several measures to increase access to testing appear effective at reducing rates of congenital syphilis in low- to middle-income countries.[27] Point-of-care testing to detect syphilis appeared to be good although more research is needed to assess its effectiveness and into improving outcomes in mothers and babies.[28]

Screening

The CDC recommends that sexually active men who have sex with men be tested at least yearly.[29] The USPSTF also recommends screening among those at high risk.[30]

Syphilis is a notifiable disease in many countries, including Canada[31] the European Union,[32] and the United States.[33] This means health care providers are required to notify public health authorities, which will then ideally provide partner notification to the person's partners.[34] Physicians may also encourage patients to send their partners to seek care.[35] Several strategies have been found to improve follow-up for STI testing including email and text messaging as reminders of appointments.[36]

Late infections

For neurosyphilis, due to the poor penetration of penicillin G into the central nervous system, those affected are recommended to be given large doses of intravenous penicillin for a minimum of 10 days.[3][12] If a person is allergic, ceftriaxone may be used or penicillin desensitization attempted. Other late presentations may be treated with once-weekly intramuscular penicillin G for three weeks. If allergic, as in the case of early disease, doxycycline or tetracycline may be used, albeit for a longer duration. Treatment at this stage limits further progression but has only slight effect on damage which has already occurred.[3]

Jarisch-Herxheimer reaction

One of the potential side effects of treatment is the Jarisch-Herxheimer reaction. It frequently starts within one hour and lasts for 24 hours, with symptoms of fever, muscle pains, headache, and a fast heart rate.[3] It is caused by cytokines released by the immune system in response to lipoproteins released from rupturing syphilis bacteria.[38]

Pregnancy

Penicillin is an effective treatment for syphilis in pregnancy[39] but there is no agreement on which dose or way of giving it is most effective.[40] More research is needed into how much antibiotic to give and when to give it.[40]

In 2012 about 0.5% of adults were infected with syphilis with 6 million new cases.[5] In 1999 it is believed to have infected 12 million additional people, with greater than 90% of cases in the developing world.[12] It affects between 700,000 and 1.6 million pregnancies a year, resulting in spontaneous abortions, stillbirths, and congenital syphilis.[4] During 2010 it caused about 113,000 deaths down from 202,000 in 1990.[6] In sub-Saharan Africa, syphilis contributes to approximately 20% of perinatal deaths.[4] Rates are proportionally higher among intravenous drug users, those who are infected with HIV, and men who have sex with men.[8][9][10] In the United States, rates of syphilis as of 2007 were six times greater in men than women; they were nearly equal in 1997.[42]African Americans accounted for almost half of all cases in 2010.[43] As of 2014, syphilis infections continue to increase in the United States.[44]

Syphilis was very common in Europe during the 18th and 19th centuries.[7] Flaubert found it universal among nineteenth-century Egyptian prostitutes.[45] In the developed world during the early 20th century, infections declined rapidly with the widespread use of antibiotics, until the 1980s and 1990s.[7] Since 2000, rates of syphilis have been increasing in the USA, Canada, the UK, Australia and Europe, primarily among men who have sex with men.[12] Rates of syphilis among American women have remained stable during this time, and rates among UK women have increased, but at a rate less than that of men.[46] Increased rates among heterosexuals have occurred in China and Russia since the 1990s.[12] This has been attributed to unsafe sexual practices, such as sexual promiscuity, prostitution, and decreasing use of barrier protection.[12][46][47]

Untreated, it has a mortality of 8% to 58%, with a greater death rate in males.[3] The symptoms of syphilis have become less severe over the 19th and 20th centuries, in part due to widespread availability of effective treatment and partly due to virulence of the spirochaete.[16] With early treatment, few complications result.[15] Syphilis increases the risk of HIV transmission by two to five times, and coinfection is common (30–60% in some urban centers).[3][12] In 2015 Cuba became the first country in the world to eradicate mother to child transmission of syphilis.[11]

History

Portrait of Gerard de Lairesse by Rembrandt van Rijn, circa 1665–67, oil on canvas - De Lairesse, himself a painter and art theorist, had congenital syphilis that deformed his face and eventually blinded him.[48]

The exact origin of syphilis is disputed.[3] Syphilis was definitely present in the Americas before European contact,[49] and it may have been carried from the Americas to Europe by the returning crewmen from Christopher Columbus's voyage to the Americas; or it may have existed in Europe previously, but went unrecognized until shortly after Columbus returned.These are referred to as the Columbian and pre-Columbian hypotheses, respectively.[21]

The Columbian hypothesis is best supported by the available evidence.[50][51] The first written records of an outbreak of syphilis in Europe occurred in 1494 or 1495 in Naples, Italy, during a French invasion (Italian War of 1494–98).[7][21] As it was claimed to have been spread by French troops, it was initially known as the "French disease" by the people of Naples.[52] In 1530, the pastoral name "syphilis" (the name of a character) was first used by the Italian physician and poet Girolamo Fracastoro as the title of his Latin poem in dactylic hexameter describing the ravages of the disease in Italy.[53][54] It was also known historically as the "Great Pox".[55][56]

The causative organism, Treponema pallidum, was first identified by Fritz Schaudinn and Erich Hoffmann in 1905.[7] The first effective treatment for syphilis was Salvarsan, developed in 1910 by Paul Ehrlich. In 1943, trials of penicillin confirmed its effectiveness.[7][55] Before the discovery and use of antibiotics in the mid-twentieth century, mercury and isolation were commonly used, with treatments often worse than the disease.[55]

The artist Jan van der Straet painted a scene of a wealthy man receiving treatment for syphilis with the tropical wood guaiacum sometime around 1580.[63] The title of the work is "Preparation and Use of Guayaco for Treating Syphilis". That the artist chose to include this image in a series of works celebrating the New World indicates how important a treatment, however ineffective, for syphilis was to the European elite at that time. The richly colored and detailed work depicts four servants preparing the concoction while a physician looks on, hiding something behind his back while the hapless patient drinks.[64]

Tuskegee and Guatemala studies

One of the most infamous United States cases of questionable medical ethics in the 20th century was the Tuskegee syphilis study.[65] The study took place in Tuskegee, Alabama, and was supported by the U.S. Public Health Service (PHS) in partnership with the Tuskegee Institute.[66] The study began in 1932, when syphilis was a widespread problem and there was no safe and effective treatment.[13] The study was designed to measure the progression of untreated syphilis. By 1947, penicillin had been shown to be an effective cure for early syphilis and was becoming widely used to treat the disease.[66] Its use in later syphilis was still unclear.[13] Study directors continued the study and did not offer the participants treatment with penicillin.[66] This is debated, and some have found that penicillin was given to many of the subjects.[13]

In the 1960s, Peter Buxtun sent a letter to the CDC, who controlled the study, expressing concern about the ethics of letting hundreds of black men die of a disease that could be cured. The CDC asserted that it needed to continue the study until all of the men had died. In 1972, Buxton went to the mainstream press, causing a public outcry. As a result, the program was terminated, a lawsuit brought those affected nine million dollars, and Congress created a commission empowered to write regulations to deter such abuses from occurring in the future.[66]

On 16 May 1997, thanks to the efforts of the Tuskegee Syphilis Study Legacy Committee formed in 1994, survivors of the study were invited to the White House to be present when President Bill Clinton apologized on behalf of the United States government for the study.[67]

^ abLozano, R (15 December 2012). "Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010.". Lancet. 380 (9859): 2095–128. doi:10.1016/S0140-6736(12)61728-0. PMID23245604.

^Anthony Grafton (March 1995). "Drugs and Diseases: New World Biology and Old World Learning". New Worlds, Ancient Texts The Power of Tradition and the Shock of Discovery. Harvard University Press. pp. 159–194. ISBN9780674618763.